The invention relates to a crucible for carrying out a multi-bath liquid phase epitaxy process in which substrates to be epitaxially coated are disposed in a slide comprising a substrate carrier, whose displacement allows the bringing the substrates successively into contact with the different epitaxy baths.
Multi-bath crucibles are used frequently in industry. They allow the treating a large number of substrates the number of baths being limited, however, to two, or the treating a considerable smaller number of substrates in a larger number of baths.
For example, the crucible described in French Pat. No. 1,600,341 filed by the Applicant belongs to the first-mentioned category. It allows the epitaxially coating of a large number of substrates arranged horizontally. By translation of a slide comprising a substrate carrier, the latter is brought into contact with one or the other of two epitaxy baths. Thus, a two-layer or a multi-layer epitaxy coating having only two types of alternate layers is thus obtained.
The crucible described in Japanese Patent Application published under No. 59-26997 (SUMITOMO) belongs to the last-mentioned category. The substrate carrier is not a single slide, but comprises three communicating and juxtaposed holding plates containing substrates to be epitaxially coated and brought by translation into contact successively with the different baths of epitaxy disposed in compartments spaced apart longitudinally. The wetting of the substrates contained in the three juxtaposed holding plates requires the application of a pressure. The use of such a crucible moreover involves difficulties because any solidification of the baths in the ducts providing for the mutual communication of the juxtaposed holding plates has to be avoided. Finally, it is not possible to treat with such a crucible a large number of substrates. An increase in the length of the holding plates leads in fact to a crucible having an unacceptable length. An increase in their width leads to difficulties during the translation of the holding plates. The crucibles are made of graphite and are therefore expensive and fragile.